Chapter 10- The Endocrine System

Groups of hormones:

1. Amino Acid Derivatives 2. Peptide Hormones 3. Lipid Derivates

The Human pituitary secretes MSH:

1. During fetal Development 2. In very young children 3. In pregnant women 4. In some diseases.

A rise in glucocorticoid levels causes a decline in the production of ____________ and __________.

ACTH and CRH

Pituitary Gland

AKA: Hypophysis -secretes nine different hormones, all of which are peptides or small proteins that bind to membrane receptors and use cAMP as a second messenger. -found in the sella turcia

Triiodothyrnine

AKA: T3 -more potent that T4 because of the three iodine atoms.

Luteininzing Hormone (LH)

FEMALES: OVULATION, FORMATION OF CORPUS LUTEUM, AND PROGESTERON SECRETION. MALES: TESTOSTERONE SECRETION

The anterior pituitary produces two gonadotropins:

Follicle-stimulating hormone (FSH) and Luteinizing Hormone (LH)

Growth Hormone (GH)

Growth, Protein synthesis, lipid mobilization and catabolism. -AKA: Human Growth Hormone (HGH) or Somatotropin

S/S of Thyrotoxic Crisis

High fever, irritability, delirium or coma, tachycardia, hypotension, vomiting, and diarrhea.

Cellular communication over greater distances is coordinated by the _____________ and ______________ system.

Nervous and endocrine

Corticosteroids: 3 distinct regions

Outer Produces: mineralocorticoids Middle Produces: glucocorticoids Inner Produces: Androgens

Antidiuretic Hormone (ADH)

Reabsorption of water, elevation of bp, and blood volume. -causes vasoconstriction-peripheral blood vessels to aid in elevating bp -kidneys -aka: vasopressin

RH

Releasing hormones -stimulate the production of one or ore hormones in the anterior hormones

What happens at high calcium ion concentrations?

Sodium permeability decreases and membranes become less responsive.

Hyperthyroidism

The presence of excess thyroid hormones in the blood.

Myxedema

a condition that reflects long term exposure to inadequate levels of thyroid hormones, with resultant changes in structure and function.

goiter

an enlarged thyroid gland. -caused by an inadequate intake of iodine which leads to an inability to synthesize thyroid hormones.

portal vessels

blood vessels that link two capillary networks, including vessels between the hypothalamus and the anterior pituitary -The entire complex is called the portal system.

hormones

chemicals messengers that are released in one tissue and transported by bloodstream to reach target cells in other tissues.

hormone receptors are found

either on the cell membrane or inside the cell.

Thyroid hormones are derived from ________________.

molecules of amino acid tyrosine to which iodine atoms have been attached.

when the metabolic rate increases.....

more heat is generated and body temperature rises.

Endocrine activity-specifically, hormonal secretion-is controlled by _________________.

negative feedback mechanisms

Treatment of Thyrotoxic Crisis in the Field

oxygen, ventilatory assistance, fluid resuscitation and cardiac monitoring. Glucocorticoids.

endocrine system

uses chemical messengers called hormones to relay information and instructions between cells.

Mineralocorticoids (MCS)

-affect

Portal systems are named after their destinations. They ensure that all of the blood that enters the portal vessels reaches certain target cells before returning to the general circulation

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Thyrotoxic Crisis (Thyroid Storm)

-Life threatening emergency that can be fatal within as few as 48H if left untreated. -associated with severe physiological stress and less with psychological. -caused by a shift of thyroid hormone in the blood from the protein-bound to the free state. Which means an increase in the amount of active hormone in circulation, and thus stimulates the thyroid gland.

Adrenocorticotropic Hormone (ACTH)

-STIMULATES THE RELEASE OF STEROID HORMONES BY THE ADRENAL CORTEX, the outer portion of the adrenal glands. -targets glucocorticoids (cells that produce hormones) which affect glucose metabolism. -Release occurs under the stimulation of CRH.

Hypogonadism

-abnormally low production of gonadotropins -children with this condition will not undergo sexual maturation, and adults with hypogonadism cannot produce function sperm of ova.

similarities between nervous and endocrine systems

-both rely on the release of chemicals that bind to specific receptors on target cells. -both share various chemical messengers; i.e. noriepi and epi are hormones in the blood and neurotransmitters in the brain. -both are regulated by negative feedback mechanisms. -both coordinated and regulate the activities of other cells, tissues, organs and systems and maintain homeostasis.

Hypothalamic Control of Anterior Pituitary

-can be controlled by RH or IH -hormones transported directly to anterior pituitary via the hypophyseal portal system. -rate of regulatory hormone secretion is regulated via negative feedback mechanism. -hormones are called "tropic hormones" (they turn on other endocrine glands)

Peptide hormones

-consist of chains of amino acids. -range from short amino acid chains (oxytocin) to small proteins (growth hormone) -includes all hormones secreted by the hypothalamus, pituitary gland, heart, kidneys, thymus, digestive tract, and pancreas.

Parathyroid Glands

-embeded in posterior surfaces of the thyroid gland.

eicosanoids

-fatty acid-based compounds derived from the 20-carbon fatty acid arachidonic acid -include the prostaglandins -coordinate local cellular activities and affect enzymatic processes in extracellular fluids including blood clotting.

Thyroxine

-hormone -contains four atoms of iodine -accounts for roughly 90% of all thyroid secretions. AKA: tetraiodothyronine or T4

Amino Acid Derivatives

-relatively small and structurally similar to amino acids (building blocks of proteins). -Includes Epi, NorEpi, Thyroid hormones, and Melatonin.

Graves' Disease

-results from the overproduction of thyroid hormone. -Hereditary -6x's more common in women than men with onset in early adulthood. -has an autoimmune origin -Glucocorticoid Therapy can help quickly reduce the T4 levels. (decadron)

Myxedema

-thickening of CT in the skin and other tissues caused by untreated hypothyroidism -classic appearance is unemotional, puffy-faced, pale, thin hair, enlarged tongue, cool skin that feels like dough. -do not actively warm pt due to contraindications of the risk of cardiac dysrhythmias and cardiovascular collapse secondary to vasodilation.

colloid

-within the cavity of the thyroid follicle- -fluid that contains large amounts of suspended proteins and thyroid hormones.

Adrenal cortex

-yellowish in color due to presence of stored lipids. -produces more than 2 dozen steroid hormones called adrenocortical steroids or corticosteroids. -without this, a person will die without corticosteroids being administered. -overproduction of these corticosteroids can have sever consequences.

Thyroid-Stimulating Hormone (TSH)

AKA: thyrotropin -TRIGGERS THE RELEASE OF THYROID HORMONES -released in response to thyrotropin-releasing hormones -as concentrations of thyroid hormones rise, the rates of TRH and TSH production declines.

S/S of hypothyroidism

Fatigue, Weight gain, cold intolerance, dry skin, hair dryness/loss, depression, dementia, muscle cramps and myalgia, bradycardia, constipation, infertility, edema, menstrual irregularity.

S/S of hyperthyroidism

Fatigue, weight loss, heat intolerance, moist skin (hyperhidrosis), hair fine and silky, nervousness, insomnia, tremor, muscle weakness,, dyspnea, tachycardia, palpations, hyperdefication, menstrual irregularity.

Oxytocin

Females: Labor contractions, milk ejection -Uterus, Mammary Glands Males: contractions of sperm duct and prostate gland -Sperm duct and prostate gland

Follicle-Stimulating Hormone (FSH)

PROMOTES FOLLICLE (AND EGG) DEVELOPMENT IN FEMALES, AND STIMULATES THE SECRETION OF ESTROGENS--STEROID HORMONES PRODUCED BY OVARIAN CELLS. -IN MALES, SUPPORTS SPERM PRODUCTION IN TESTES. -releases inhibin

Liver cells respond to the presence of growth hormone by synthesizing and releasing _______________ or ____________________.

Somatomedins or insulin-like growth factors

Prolactin (PRL)

Stimulate mammary gland development and milk production.

Thyrotoxic Crisis

a condition that reflects the prolonged exposure of a body organs to excess thyroid hormones, with resultant changes in structure and function. -Generally caused by Grave's Disease.

S/S of Graves' Disease

agitation, emotional liability, insomnia, poor heat tolerance, weight loss despite increased appetite, weakness, dyspnea, and tachycardia or new-onset afib without a cardiac history.

The binding of thyroid hormones to mitochondria increases the rate of ATP production. Thyroid Hormone-receptor complexes in the nucleus activate gene coding for synthesis of enzymes involved in glycolysis and energy production, resulting in......

an increase in cellular rates of metabolism and oxygen consumption. -because the cell consumes more energy, and energy use is measured in calories, the effect is called the calorgenic effect of thyroid hormones.

Posterior Pituitary Gland

contains axons from two different groups of neurons located within the hypothalamus. 1. Antidiuretic Hormone (ADH) 2. Oxytocin

Anterior Pituitary Gland

contains endocrine cells surrounded by an extensive capillary network. -provides entry into the circulatory system. -part of they hypophyseal portal system

In adipose tissue, the growth hormone stimulates the breakdown of stored fats and the release of ________________ into the blood. In turn, many tissues stop breaking down glucose and start breaking down fatty acids to generate ATP.

fatty acids

endocrine cells

glandular secretory cells that release their secretions into extracellular fluid.

Gonadotropins

group of hormones that regulates the activities of the male and female sex organs, or gonads. -production is stimulated by gonadotropin-releasing hormone from the hypothalamus.

Calcitonin

helps regulate calcium ion concentrations in body fluids. -Inhibits osteoclasts and stimulates calcium excretion at the kidneys.

receptor

hormone receptors are located either on the cell membrane or inside the cell.

Somatomedins

increase the rates at which amino acids are taken up and incorporated into new proteins.

Melanocyte-Stimulating Hormone (MSH)

increased melanin synthesis in epidermis.

IH

inhibiting hormones -prevent the synthesis and secretion of pituitary hormones.

What unites the two lobes of the thyroid gland?

isthmus -the extensive blood supply of the thyroid gland gives it it's deep red color.

Steroid Hormones

lipids derived from cholesterol -released by the reproductive organs and adrenal glands. -insoluble in water and bound to specific proteins in the blood.

because epi, norepi and the peptide hormones are not lipid soluble, they cannot diffuse through a cell membrane, and they bind to receptor proteins on the _________ surface of the cell membrane. Eicosanoids which are lipid-soluble, diffuse across the cell membrane and bind to receptor proteins on the ___________ surface of the cell membrane.

outer inner

Insulin-like growth factors (IGF)

peptide hormones that bind to receptor sites on a variety of cell membranes.

infundibulum

piece that the pituitary gland hangs from the hypothalamus by.

target cells

respond to the presence of the hormone received. -sensitivity is determined by the presence or absence of a specific receptor with which a given hormone interacts.

exocrine cells

secrete onto epithelial surfaces.

Adrenal Glands

sits on the superior border of each kidney. has two parts: 1. Adrenal cortex 2. adrenal medulla

What happens at low calcium concentrations?

sodium permeabilities increase and muscle cells and neurons become extremely excitable. -could cause convulsions or muscle spasms. (such actions are prevented by the parathyroid gland)

thyroid follicles

spheres lined by a simple cuboidal epithelium

In males, LH is called interstitial cell stimulating hormone because it stimulates the interstitial of cells of the testes to produce sex hormones. These sex hormones are called androgens and the most important is ___________________________.

testosterone.

Hypothyroidism

the presence of inadequate thyroid hormones.

Two classes of regulatory hormones:

1. Releasing hormones (RH) 2. Inhibiting Hormones (IH)

Hormones of the anterior pituitary

1. TSH 2.ACTH 3. FSH 4. LH 5. PRL 6.GH 7.MSH

methods of controlling endocrinal activity

1. humoral stimuli-changes composition of extracellular fluid. i.e. parathyroid hormone & calcitonin 2. hormonal stimuli-changes in the levels of circulating hormones 3. Neural stimulation-results from

hormones alter cellular operations by changing the ____________, ______________, _______________, or ____________ of important enzymes and structural proteins in various target cells.

1. identities 2. activities 3. locations 4. quantities

The hypothalamus provides the highest level of endocrine control by acting as an important link between the nervous system and endocrine system. Coordinating centers in the hypothalamus regulate the activities of the nervous and endocrine system in three ways:

1. secrete regulatory hormones, which are special hormones that control the activity of endocrine cells in the anterior pituitary gland. 2. acts as an endocrine organ by synthesizing two hormones, ADH and Oxytocin. 3. the hypothalamus contains autonomic nervous system centers that control endocrine cells of the adrenal medullae through sympathethic innervation.

Two Classes of Lipid Based Hormones

1. steroid hormones 2. eicosanoids

LH promotes the secretion by the ovaries of ______________ and ______________.

estrogens and progestin's - which prepare the body for possible pregnancy.

what produces Thyroid hormones?

follicular epithelial cells and stored within the follicle cavities.

C cells (parafollicular cells)

produce calcitonin -release calcitonin when the calcium ion concentration of the blood rises above normal. The target organs are the bones and kidneys. -turns off when calcium levels return to normal via calcitonin.

all cellular structures and functions are determined by __________.

proteins proteins determine shape & structure while enzymes determine metabolism.

Freely circulating hormone

remains functional form 2 minutes - 1 hour. -are inactivated when: 1) they diffuse out of the blood stream and bind to receptors on target 2) they are absorbed and broken down by certain liver or kidney cells 3)they are broken down by enzymes in the plasma or interstitial fluids. -Steroid hormones and thyroid hormones remain in circulation much longer because almost all become attached to special transport proteins.